ON THE RABICIDAL PROPERTY OF ANTI-RABIES SERUM

The investigations just outlined indicate that1. The anti-rabies serum from animals artificially immunized possesses a specific rabicidal property, while no other antibodies can be found in it.2. The serum from animals immunized by repeated injections with normal nerve material has a non-specific property against rabic virus. 3. The rabicidal property of serum from naturally immune (refractory) animals can be a direct index of resistance against rabies infection.4. The union of rabic virus with anti-rabies serum takes place in multiple proportion as in the case of toxin and antitoxin. This fact indicates that even a slight degree of resistance against rabies in an individual can be detected by titrating the serum of the individual with a small dose of virus. From a practical point of view, it would be very interesting to indirectly standardize the value of a rabies vaccine by titrating the rabicidal property of serum taken from animals inoculated with the vaccine.5. The rabicidal property of the anti-rabies serum vanishes by heating at 80°C. for one-half hour, while no change takes place in rabicidal power of the serum by heating below 70°C. for onehalf hour.6. The optimum temperature and time for the union of rabic virus with anti-rabies serum are 37°C. and two hours respectively. A somewhat similar result is obtained by storing them at a temperature of from 18°-20°C. for twenty hours in a dark room.7. The protective injection of the anti-rabies serum into guinea-pigs inoculated with rabic virus has given satisfactory results. This may throw a light on the problem of utilizing anti-rabies serum for protective or curative purposes.